JPH05123200A - Preparation of galactooligosaccharide - Google Patents

Abstract

(57) [Summary] [Objective] To provide a method for advantageously extracting oligosaccharides from soybean hypocotyl, which is industrial waste. [Structure] Soybean seed hypocotyl is used as a raw material, and this is mixed and stirred in an acidic aqueous solution of pH 3 to 6 to extract oligosaccharides such as raffinose and stachyose.
Method for preparing galactooligosaccharide. [Effect] It is generated as a by-product during the recent tofu production,
This has the effect that oligosaccharides can be advantageously extracted from the hypocotyl of soybeans that have been mostly disposed of, and that soybean hypocotyl, which is an industrial waste, can be effectively used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preparing a galacto-oligosaccharide, and more particularly to a method for preparing an inexpensive and simple galacto-oligosaccharide using hypocotyl, which has been conventionally generated as a by-product during soybean treatment.

[0002]

2. Description of the Related Art Conventionally, many oligosaccharides are known as active factors of bifidobacteria, which are said to have good intestinal-regulating effects among human intestinal bacteria. It is said that the oligosaccharides assimilated by Bifidobacteria have a molecular weight of 5 to 6 or less, and among these oligosaccharides, galactooligosaccharides extracted from soybean, that is, raffinose and stachyose are generally other oligosaccharides. It is said that its activity is higher than that of sugar.

By the way, the hypocotyl of soybean is generated as a by-product in the recent production of tofu, but it has not been effectively used and is normally discarded. In the future, it is inevitable that the hypocotyl generated as a by-product will increase as the production amount of tofu increases.

Various methods have been proposed for extracting oligosaccharides from soybeans. For example, as in the inventions of JP-A-59-179064 and JP-A-60-66978, once extraction is performed using water, Soy milk is prepared from soybeans or defatted soybeans, and proteins present in the soy milk are removed by precipitation to prepare oligosaccharides. Further, in Japanese Patent Application Laid-Open No. 62-155082, soybeans are defatted and then oligosaccharides are extracted using a 20 to 60% ethanol aqueous solution. Furthermore, since a large amount of oligosaccharides is contained in whey produced as a by-product during the production of alcohol-enriched soybean protein, extraction from this whey is also performed.

However, in such a method, removal of impurities and treatment of ethanol are costly and complicated, and it is difficult to obtain inexpensive oligosaccharides. In addition, there has been no example of extracting oligosaccharide from soybean hypocotyl.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a simple and inexpensive method for extracting oligosaccharides from hypocotyls, which have been conventionally disposed of as industrial wastes, in a state of low impurity content. However, the soybean hypocotyl, which will become more and more problematic as these industrial wastes, will be effectively utilized.

[0007]

Means for Solving the Problems As a result of intensive studies in view of the above points, the present inventor has found that a soybean hypocotyl, which has been conventionally disposed of or used only for feed or fertilizer, has a certain pH range. Thus, the present invention has been completed by utilizing the fact that the protein contained therein is insolubilized by precipitation.

That is, the present invention uses a soybean seed hypocotyl as a raw material, and mixes and stirs this in an acidic aqueous solution having a pH of 3 to 6 to extract oligosaccharides such as raffinose and stachyose. A method for preparing sugar.

The outline of the preparation method of the present invention will be described. After crushing the hypocotyl separated from soybean, defatting is performed to obtain a defatted hypocotyl. The solvent used for this degreasing may be any solvent that is generally used for extracting edible oils and fats such as hexane, and is not particularly limited.

The defatted hypocotyl thus obtained is mixed and stirred in an acidic aqueous solution of pH 3 to 6, preferably 4 to 5. If the pH value of the aqueous solution deviates from the above range, the amount of impurities in the extract increases, which is not preferable.

During the mixing, an acid such as hydrochloric acid is added in advance so that the pH value of the mixed solution becomes 3 to 6, preferably 4 to 5.
It is preferred to mix the pH adjusted acid solution.

The amount of the aqueous solution to be mixed is preferably about 4 times the defatted hypocotyl. If the amount of the aqueous solution is small, the operation can be simplified in the subsequent drying step, but it becomes difficult to stir during extraction or separate the extract. On the other hand, when the amount of the aqueous solution is large, stirring is easy and the extraction efficiency and the yield at the time of separation are increased, but the amount of water to be removed in the drying step is large, resulting in cost increase. Therefore, the amount of the aqueous solution to be mixed may be appropriately determined in consideration of these situations.

The temperature during the extraction step is 20 ° C to 80 ° C, preferably 40 ° C to 60 ° C. If the temperature is too low, the extraction efficiency is lowered, and if the temperature is too high, the extraction efficiency is improved. However, the browning or oligosaccharide hydrolysis by sugars and amino acids occurs, and therefore the above temperature range is preferable.

By extracting under the above conditions, most of the proteins as impurities are precipitated. After this step, solid-liquid separation is performed by an appropriate means such as centrifugation or filtration to obtain an oligosaccharide extract. The extract thus obtained is a liquid containing a small amount of protein and having a high concentration of oligosaccharide. In addition, the precipitated protein contains a large amount of substances that behave similarly to the protein during precipitation, and oligosaccharides containing less impurities are extracted.

[0015]

EXAMPLES Hereinafter, the effects of the present invention will be further clarified by exemplifying examples, but this is an example and the spirit of the present invention is not limited by these examples. In addition,
All parts and% in the examples mean weight basis.

Examples 1 to 7 and Comparative Examples 1 to 100 parts of defatted soybean hypocotyl were added 400 parts of an acidic aqueous solution having each pH shown in the table below, and the mixture was subjected to stirring extraction at room temperature for 1 hour and then centrifuged. Separation (10000 G, 20 min) was performed to separate the extract. The acidic extract was neutralized with sodium hydroxide and then dried to obtain an extract. The properties of this extract are as follows.

Table-1 ──────────────────────────────────── Experiment Extraction Yield Ash Content Crude Protein Total Sugar amount Rafino Stacchio No. pH (%) (%) (%) (%) Sose (%) Sose (%) ────────────────────── ─────────────── 1 1.0 50.3 11.3 50.6 29.8 4.17 19.7 2 2.0 45.5 10.5 47.3 32.9 5.10 22.7 3 3.0 42.6 8.7 20.5 55.8 9.14 38.0 4 3.5 40.3 8.6 18.4 58.0 9.74 40.7 5 4.0 38.6 5.2 16.3 63.0 10.4 44.5 6 4.5 37.2 5.1 15.2 64.1 10.9 45.0 7 5.0 36.8 4.2 20.5 61.0 10.1 42.7 8 5.5 40.2 4.5 23.0 58.1 9.37 41.2 9 6.0 47.2 3.5 50.7 37.0 6.19 26.3 10 7.0 50.3 3.5 61.4 29.7 3.89 16.9 ───── ───────────────────────────────

(Note) All analytical values are% per dry matter. However, the ash content was measured at 600 ° C as an ignition residue, the crude protein was measured by the Kjeldahl method, the total sugar amount was measured by the phenol-sulfuric acid method, and each oligosaccharide was measured by high performance liquid chromatography (column: Asahi Pack NH2P-50, elution Liquid is acetonitrile: water = 85: 15, detector is JASCO 830RI, flow rate is 0.5m.
(Measured at l / min).

As is clear from the results in the above table, when oligosaccharides were extracted from the defatted soybean hypocotyl with an acidic aqueous solution of pH 3 to 6, the extract contained less protein and produced less ash during neutralization. On the contrary, the total sugar amount is large, and especially the raffinose and stachyose contents are high (Experiment Nos. 3 to 9). On the other hand, when the extract is extracted in the neutral region or under a strong acidity of pH 2 or less, the ash content and the crude protein in the extract are large and the amount of impurities is large (Experiment Nos. 1-2 and 10). Experiment No. 3 ~
9 are Examples 1 to 7, respectively, and Experiment Nos. 1 to 2 and 10
Are Comparative Examples 1 to 3, respectively.

As described above, according to the preparation method of the present invention, the drug or time used for the subsequent purification can be saved as compared with other extracts.

Example 8 In Experiment No. 6 of the previous example, sulfuric acid was used as the acid used and calcium hydroxide was used as the alkaline agent at the time of neutralization. After that, centrifugation (10000 G, 20 min) was performed, and after drying, the same analysis as in the previous example was performed.

The results are as follows. For comparison, the results of Experiment No. 10 (pH 7 during extraction, sodium hydroxide used for neutralization) and Experiment No. 6 (hydrochloric acid used during extraction, sodium hydroxide used for neutralization) were compared for comparison. Also written.

Table-2 ──────────────────────────────────── Experiment Extraction Yield Ash Content Crude Protein Total Sugar amount Rafino Stacchio No. pH (%) (%) (%) (%) Sose (%) Sose (%) ────────────────────── ─────────────── 10 7.0 50.3 3.5 61.4 29.7 3.89 16.9 6 4.5 37.2 5.1 15.2 64.1 10.9 45.0 11 4.5 36.6 4.2 12.5 69.3 11.7 48.5 ─────────── ────────────────────────

As a result, when sulfuric acid is used for pH adjustment and calcium hydroxide is used for neutralization, the neutralized salt precipitates, the ash content contained in the extract is small, and the precipitation of protein due to calcium is also produced at the same time. And a higher-purity extract was obtained (Experiment No. 11). Experiment No. 11 is Example 8.

From the above results, it is clear that when sulfuric acid is used for pH adjustment, impurities are reduced, so that the subsequent steps are simplified and the amount of drug used for purification can be reduced.

[0026]

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide a simple and inexpensive method for extracting oligosaccharides from soybean hypocotyls, which have been conventionally discarded as industrial wastes, in a state where the content of impurities is low. Therefore, it has the effect of effectively utilizing soybean hypocotyls, which will become more and more problematic as these industrial wastes in the future. And, the present invention, as in the conventional method, has much less protein present in the extract than the extraction of oligosaccharides from soymilk, and therefore the amount of protein coagulants such as calcium chloride used during purification can be considerably reduced. In addition, when sulfuric acid is used as an acid used for pH adjustment, by using an alkali that produces a water-insoluble substance such as a calcium-neutralizing salt for neutralization, ion-exchange resin etc. used in the subsequent desalting step The amount of drug can be reduced. The above steps are simpler than those for preparing oligosaccharides from alcohol-enriched soy protein whey, because the ethanol recovery operation required when separating and purifying from alcohol-enriched soy protein whey is unnecessary. It has an effect.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuo Hattori 4-2-3 Matsumaedai, Moriya-cho, Kitasoma-gun, Ibaraki A-207 (72) Hiroko Kurita 1-12 Matsumae-dai, Moriya-cho, Kitasoma-gun, Ibaraki -1 (72) Inventor Chiemi Takei 1-12-4 Matsumaedai Moriya-cho, Kitasoma-gun, Ibaraki Prefecture Inventor Yoko Yoko Sato 5-7-1 Kinnodai, Yawahara-mura, Tsukuba-gun, Ibaraki Prefecture

Claims (1)

[Claims] 1. A soybean seed hypocotyl is used as a raw material, which is adjusted to pH 3
A method for preparing a galacto-oligosaccharide, which comprises mixing and stirring in an acidic aqueous solution of Nos. 6 to 6 to extract oligosaccharides such as raffinose and stachyose.